1. Field of the Invention
The present invention relates generally to an aluminum frame member, such as a transverse frame member, vertical frame member or so forth, for forming a curtain wall, or sash.
2. Description of the Related Art
Typically, an aluminum frame member for a sash is colored into white, silver, black, gold or so forth by performing a surface treatment, such as anodic oxide film coating, on an extruded frame material.
In the area near the sea, corrosion of the aluminum frame member is accelerated due to salt damage. As a solution for this, Japanese Unexamined Utility Model Publication No. Hei 3-8219 discloses an aluminum frame member to which a fluorocarbon resin coating is applied on the exterior side surface to be exposed to the exterior after performing a surface treatment so as to improve weather-proof capacity.
In performing a surface treatment for coloring the extruded frame material, since the color on the overall surface becomes a uniform color so that the interior side surface and the exterior side surface of the aluminum frame member become the same color. Therefore, a sash formed by such aluminum frame member becomes the same color at the interior side and the exterior side. When different colors at the interior side and the exterior side are desired, it becomes necessary to perform the surface treatment with masking for one side which is not to be colored with one of the colors. Such surface treatment is cumbersome and labor-intensive.
In case of the aluminum frame member with the fluorocarbon resin coating on the exterior side surface exposed to the exterior for avoiding accelerated corrosion due to salt damage or so forth, the fluorocarbon resin coating operation has to be performed after performing a surface treatment on the overall surfaces. Such process is very cumbersome and labor-intensive.
This problem may be solved by performing the fluorocarbon resin coating on the overall surface of the aluminum frame member by way of surface treatment. However, since the fluorocarbon resin coating varnish is very expensive, the aluminum frame member with the fluorocarbon resin coating on the overall surface inherently becomes unacceptably expensive.